Nonlinear dielectric effect in benzonitrile and lauronitrile solutions

The nonlinear dielectric effect, NDE, and the calculated correlation factors R^p and R^s are reported for binary solutions of benzonitrile and lauronitrile in benzene and cyclohexane. Substantial differences found for solutions in these two solvents have been explained in terms of critical phenomena in cyclohexane solution.     

Nonlinear dielectric effect in carbon tetrachloride solutions of iodobenzene

The results of measurements of Δ/E² as a function of concentration for CCl₄ solutions of iodobenzene are given and compared with earlier results for CCl₄ solutions of fluoro-, chloro- and bromo-benzene. Terms contributing to the molar saturation constant for pure halogeno-derivatives of benzene have been calculated, using Kielich's theory. The change of sign of Δ/E² for bromo- and iodo-benzene is explained.     

Nonlinear dielectric effect of phenyl and methyl isothiocyanates in benzene and carbon tetrachloride

The nonlinear dielectric effect (NDE) of phenyl isothiocyanate and methyl isothiocyanate in benzene and carbon tetrachloride as solvents has been investigated. A different NDE dependence on the concentration for both investigated isothiocyanates and a significant solvent effect in the case of methyl isothiocyanate were observed.     

Thermodynamic functions of the mixing of acrylic acid solutions in hexane,benzene, and acetonitrile

The saturated vapor pressure over solutions of acrylic acid in hexane, benzene, and acetonitrile was measured tensimetrically over a temperature range of 295 to 355 K. The composition of the equilibrium phases, the activity coefficients of the components, and the thermodynamic functions of mixing (H ^E , G ^E , and S ^E ) of the solutions under study were calculated using the data on temperature dependence. A connection was established between the heat and Gibbs energy of mixing and the physical properties of the solvents.     

Low-density polyethylene in mixtures of hexane and benzene derivates

Preferential sorption, equilibrium swelling degree, and volume of the swollen membrane in systems low-density polyethylene + hexane + aromatic compound (benzene, methylbenzene, or ethylbenzene) were studied using gravimetric and dilatometric methods at the temperature of 25 °C. Aromatic compounds are preferentially sorbed in low-density polyethylene compared to hexane. Experimental volume changes of the membrane were found to be noticeably different from those calculated on the basis of mass sorption data under the assumption of additivity. This difference points to the existence of the interactions between the polymer and the surrounding liquid mixture. The volume swelling degree curves are close to each other in the whole concentration range of the binary liquid mixture (hexane + aromatics) suggesting that the attractive forces between the polymer chains are the deciding factor limiting the volume expansion of the membrane in all three systems to the same extent.     

Nonlinear dielectric effect in a critical solution

This paper presents measurements of Δ/E² versus T for the critical solution nitroethane in cyclohexane. The Δ/E² for the temperature near the critical temperature T_c has a positive value and satisfies the following dependence: Δ/E² ∝ 1/(T ? T_c)^λ where λ = 0.34.     

Nonlinear dielectric effect (NDE) and molecular orbital study of the conformational equilibrium in 1,4-dimethoxybenzene in benzene solution

The conformational equilibrium in 1,4-dimethoxybenzene (1,4-DMB) in benzene solutions has been studied. On the basis of experimental values of the nonlinear dielectric effect (NDE) parameter, electric permittivity and density, determined in this work, and applying the general statistical theory of NDE, the contributions of the syn-anti and syn-syn conformers and the electric dipole moment of the polar syn-syn conformer were calculated. The molecular orbital method (PM3) has also been applied for calculation of the dipole moments and energies of particular conformers. The results of the NDE study and PM3 calculations are consistent and they reveal the existence of two conformers (syn-anti and syn-syn) of comparable energy values, but different values of dipole moments, and the predominance of the polar form (syn-syn) of the mole fraction in benzene. Moreover, the energies of intermolecular interactions have been determined from the concentration dependence of linear and nonlinear polarisability.     

Luminescent determination of automobile petrol in hexane solutions

The work deals with the problem of determination of automobile petrol of various octane numbers and petroleum contamination of some objects on the basis of analysis of photoluminescence spectra of automobile petrol samples. For this purpose steady state luminescence properties of samples of automobile petrol of different types being in sale were measured. Samples of automobile petrol diluted in hexane were prepared and their luminescence spectra were measured at room and liquid nitrogen temperatures of samples. We constructed concentration dependences of luminescence intensity of both wide band luminescence of liquid solutions obtained at room temperature and peak intensities of luminescence lines of quasi linear spectra of solutions frozen at 77 K. Possibility to use luminescence method for analysis of petrol pollutions on some objects is illustrated by results of investigation of pine-wood pieces contaminated by automobile petrol.     

Nonlinear dielectric effect near the critical point of binary mixtures

The nonlinear dielectric effect (NDE) was measured in two binary systems near the critical point. The effect of independent of specific dipole-dipole interactions in contrast with previous conceptions. Its singular part is proportional to (T ? T_c)^{?$\text{1}\text{2}$} in agreement with Snider's theory as applied to NDE.     

Pseudospinodal curve for binary solutions determined from the non-linear dielectric effect

Non-linear dielectric effect (NDE) measurements were used to determine the pseudospinodal curves for nitrobenzene—hexane and benzonitrile—hexane solutions. Values obtained for universal magnitudes describing pseudospinodals are in good agreement with theoretical predictions and with experimental values found by other methods. The power exponent describing the temperature changes of NDE decreases with increasing distance from the critical concentration.     

Solubility of benzene in aqueous solutions ofmyo-inositol

Solubilities of benzene in aqueous solutions of myo-inositol have been obtained at 15, 25, 35, and 45°C. Large ‘salting-out’ effects are observed, indicating that the inositol is as effective as the common strong electrolytes in decreasing the solubility of benzene. The results are intepreted by a simple model involving the hydration number of inositol as an adjustable parameter. Hydration numbers varying from 14.4 at 15°C to 9.1 at 45°C are reported.     

Density,partial molar volume,and excess volume of solutions of acrylic acid in acetonitrile, 1,2-dichloroethane,hexane, and benzene at 293 K

Using pycnometric method, we have measured density of the solutions of acrylic acid in acetonitrile, 1,2-dichloroethane, hexane, and benzene at 293 K and atmospheric pressure. The values of the excess molar volume for these systems and the values of the partial molar volumes of components were derived. In the whole concentration range the excess molar volume for binary mixtures of acrylic acid and either 1,2-dichloroethane, or benzene, or hexane has positive values, and in the system of acrylic acid-acetonitrile the value is negative.     

The impedance of solutions of AOT/water micelles in hexane

Broadband dielectric spectroscopy was used to study the electric properties of solutions of reverse AOT/water micelles in hexane. An analysis of the frequency dependences of the complex electric modulus allowed us to find the region of frequencies in which dc-conductivity was observed and exclude the region of electrode effects. At frequencies f of ～ 10⁴Hz, the field dependences of dc-conductivity changed from linear (the Ohm law) to quadratic (the Mott law) as the volume fraction of micelles increased. This was evidence of a strengthening of the effect of current limitation by a volume charge. The upper and lower limits of the drift mobility of carriers μ responsible for dc-conductivity were estimated as 0.1 cm^?2 V^?1 s^?1 < μ < 0.3 cm^?2 V^?1 s^?1, which was close to the mobility of electrons in hexane. This allowed us to relate the nature of current carriers to that of free electrons; the activation energy of electron creation was found to be E _a ≈ 0.41 eV. The electron lifetime up to its trapping by acceptors was estimated. The results obtained and the literature data on the rate constants of such reactions led us to conclude that micelles were capable of absorbing acceptor impurities from solvents (additional solvent purification).     

Vibrational relaxation of phenol in benzonitrile and benzene solutions

The Raman bandwidths and the frequency shifts of the ν₁₂(A₁) mode and the IR ν₃(OH) stretching mode of phenol and phenol-OD have been measured as a function of concentration in benzonitrile and benzene solutions. Opposite isotope effects of deuterium substitution in the hydroxyl group of phenol on the bandwidths of the ν₁₂ and the ν₃(OH) modes have been found. The experimental bandwidths are discussed in terms of available theoretical models for dephasing and other mechanisms of broadening. The isolated binary collision dephasing model of Fischer-Laubereau, the Knapp-Fischer concentration-fluctuation model and the Robertson-Yarwood model have been tested. It has been stated that the purely repulsive potential is responsible for vibrational dephasing of the ν₁₂ mode of phenol in benzene while the concentration-fluctuation model reproduces the experimental data for that mode in benzonitrile. The coupling between the ν₃(OH) and ν₂(OH…N) modes is the dominant mechanism for broadening of the ν₃(OH) mode of phenol in benzonitrile.     

Oxidation of benzene by ozone in aqueous solutions

The rates of reaction between benzene and ozone were measured at temperatures varying from 5 to 35 °C in aqueous solutions in the pH range 3–7 utilizing the stopped-flow technique. The ozonation reaction was one-half order with respect to the concentration of both ozone and benzene in acidic solutions. In neutral solutions, however, the reaction was first order in ozone concentration and nearly independent of benzene concentration. At 25 °C the half-life of the reaction decreased from about 20 to less than 0.2 s and the first-order rate constant increased from 0.012 to 12.2 s⁻¹ as the pH value of the solutions increased from 3 to 7.Both benzoquinone (p-quinone) and hydroquinone (1,4-dihydroxybenzene) were formed in the neutral solutions as detected with a gas chromatograph. In the acidic solutions, however, only benzoquinone was found. The activation energies at pH values of 3 and 7 respectively were estimated to be 20.9 and 3.3 kcal mol⁻¹. A shift in the mechanism of the reaction is suggested by the results.     

Infrared spectrum of benzene in bromine and carbon tetrachloride solutions

The benzene—bromine complex at room temperature has been re-studied by infrared with bromine in excess of benzene. Solutions of 0.225 M benzene in bromine—carbon tetrachloride mixtures were studied. Under this condition, the spectral changes of measurable benzene absorption bands were observed more clearly than previously. The out-of-plane vibrations of benzene were observed to shift to higher frequencies. The equilibrium constant was found to be 0.11 ? mole^?1. The accord with the equilibrium constant derived from benzene rich systems supports the concept of a specific interaction. A C_6V symmetry is favoured for the geometry of the complex.     

Microwave dielectric relaxation in some hydrogen-bonded solutions

Dielectric constant and loss values have been obtained between 1 and 35 GHz for several:polyhydroxyl alcohols in p-dioxane solution at 25°C. The data have been analyzed in terms of a Cole-Cole distribution. The relaxation times are sensitive to the proximity of the hydroxyl groups and the degree of intramolecular hydrogen bonding.